In many regions, depending on geological and meteorological conditions, the likelihood exits that motor vehicles will encounter situations where the driving wheels thereof become embedded in snow, mud, sand, or the like. The traction required for moving the vehicle may become greater than the drive wheels can create. The result often is that the vehicle ceases to progress forward. Thereafter, repeated attempts to move the vehicle forward or backward causes ruts of irregular configuration to form, and the vehicle to become entrapped therein.
Attempts to extract the vehicle by using inflexible fixed-length planar surfaces, such as (in the most primitive form) wooden boards, are often ineffectual. First of all, it may be difficult to get a sufficiently long board both into the rut and under the tire. Secondly, the planar board or the like needs to be placed with one end under the tire and the other end out of the rut. However, this can cause the planar traction device to be angled upward to a degree (depending on the depth of the rut) which itself prevents the wheel from gaining increased traction. Finally, if the vehicle is backed up to the rear of the rut so that an inflexible traction device can be inserted under it at a low angle, driving forward can cause the traction device to collapse in its unsupported middle under the weight of the car.
In such situations, it can be important for a stranded motorist to have available means for extracting the vehicle without outside assistance. A suitable traction apparatus needs to be compact, lightweight, durable, and configured for ready application in ruts of varying depth and profiles.
Prior developments in this field may be generally illustrated by reference to U.S. Pat. No. 4,261,510, which describes a vehicle wheel traction device comprising an elongated body plate of a width somewhat greater than the width of the vehicle tire with which the device is used. The stated length of the device is 22 inches. Fastened transversely and in spaced relationship along the length of the plate are a plurality of bars or beams constituting a gripping surface for the wheel, and, on the reverse side of the plate, a plurality of similarly shaped but diametrically-opposed bars. The latter bars are for gripping the soft material (snow, mud, sand, and the like) simultaneously as the wheel is driven along the traction device over the soft material from which the embedded wheel is to be dislodged. The teachings of this patent are hereby wholly incorporated by reference herein.
The device of U.S. Pat. No. 4,261,510, while providing many good qualities, has been found to suffer the disadvantages common to inflexible fixed-length devices as described above. Namely, if the device is made in a length adequate to allow the vehicle to build up momentum, as taught in said patent, it may be difficult to put in place, especially at a proper angle; it may be bent or broken by the weight of the car; and it takes up excessive room in a car trunk.